拼合珊瑚的鉴定特征

珠宝市场上见到的大尺寸珊瑚有增多趋势,这类珊瑚多为珊瑚小料和胶结物拼合而成,前人研究未对其鉴定特征进行系统总结.笔者结合长期宝石检测工作认识,对目前市场上常见的两类拼合珊瑚的鉴定特征进行了系统研究和阐述.其中,一类拼合珊瑚由珊瑚小料和胶结物组成,另一类拼合珊瑚由珊瑚小料、人工胎体材料和胶结物组成.放大检查和紫外荧光观察发现,拼合部位的胶结物、胎体材料与主体红珊瑚在外观及发光性特征上存在差异明显;红外光谱测试结果进一步确定胶结物的主要成分为甲基丙烯酸甲酯和环氧树脂,部分拼合珊瑚依附的胎体材料主要为醇酸树脂（掺有碳酸盐粉末）和氰基丙烯酸乙酯.结果表明,放大检查、紫外荧光观察和红外光谱测试的综合运用,能够快速、准确、有效地鉴别拼合珊瑚.     

数字技术在航空伽马能谱仪中的应用

基于峰值采样保持的模拟能谱仪无法满足大尺寸多晶体高计数率的航空能谱测量。本系统采用了Y/U双通道数控增益放大器实现了谱漂的双16位分辨率调节范围,通过高速ADC与CPLD实现数字化能谱仪,在CPLD内部用VHDL语言编程实现基线恢复与峰高数据采集,保证了能量分辨率。结果表明:计数最大通过率大于100k/s,1 024道分辨率137Cs峰谱漂±1道,能量起始阈20 keV。实验证明本系统功耗低,性能可靠,体积小,可应用于航空能谱测量的场合。     

Adsorption behaviors of Cd^2＋ on Fe2O3/MnO2 and the effects of coexisting ions under alkaline conditions

This study describes the adsorption features of cadmium on Fe2O3 and MnO2 in alkaline saline conditions. The adsorption reached equilibrium in 6 hours under alkaline conditions. The absorption of cadmium on Fe2O3 and MnO2 was consistent with Freundlich absorption isotherms, and the corresponding adsorption capacities were 16.3 and 16.7 mg·g-1, respectively. Moreover, the adsorption quantity of cadmium on Fe2O3 and MnO2 rose with increasing pH from acidic to neutral, and reached the maximum at pH= 9. The coexisting chlorides reduced the adsorption capacity of Fe2O3 and MnO2. The influence intensities of different cations follow the order of CaCl2>>KCl>NaCl. However, the influence of sodium salts on the capacities of Fe2O3 and MnO2 to adsorb cadmium appeared more complicated: the relatively low concentrations of sodium salts could reduce the adsorption capacity; with increasing concentrations of sodium salts, e.g. NaCl and NaNO3. The adsorption capacity decreased continually. Moreover, due to the competition adsorption and precipitation effects, the adsorption capabilities of Na2CO3, NaH2PO4 and Na2HSO4 could also be reduced and cadmium concentrations in the solution were reduced as well.     

微量石棉的X射线衍射定量检测

微量(质量分数低至0.1%)石棉的定量分析是一世界性难题。研究了自行车、电动车车闸等摩擦材料中石棉含量为0.1%~5.0%(质量分数)的X射线衍射定量分析方法。对含有微量石棉的样品通过X射线衍射的基底吸收修正法,求出定量分析试样中的石棉含量,计算出石棉的比例。研究成果对支持我国自行车、电动车等产品出口日本的工作具有现实意义。     

次灵敏线-火焰原子吸收光谱法连续测定 高品位矿石中的铜铅锌量

[摘要]分别以铜327郾4 nm 和249郾2nm、铅283郾3 nm 和261郾4nm、锌307郾6nm 次灵敏线为分析线, 火焰原子吸收光谱法测定了高品位矿石中铜、铅、锌的含量。考察了高品位矿石基体及主要杂质的干扰 情况,结果表明,铜、锌质量浓度小于2 mg/ ml 时,对铅的测定无干扰;铅质量浓度小于2 mg/ ml 时,对铜 测定无干扰,其质量浓度小于0郾5mg/ ml 时,对锌测定无干扰;测定溶液中主要杂质铁、钴、镍、钙、镁质量 浓度在1mg/ ml,铝、硅质量浓度在0郾2mg/ ml 对测定无干扰。铜铅锌的质量浓度分别在0 ~ 1000滋g/ ml 范围内呈良好的线性关系。方法的精密度(RSD,n=5) 小于5%,加标回收率在98郾91% ~ 101郾08%,测 定铜铅锌矿石国家标准物质,结果与标准值相符。     

Raman spectra of nitrogen-containing organic compounds obtained in high altitude sites using a portable spectrometer: Possible application for remote robotic Titan studies

Well-resolved Raman spectra of examples of nitrogen-containing compounds were detected using a portable Raman instrument (Ahura First Defender XL) outdoors at a low temperature of −15 °C at an altitude of 2860 m (Pitztall, Austria). The portable Raman spectrometer tested here is equipped with a 785 nm diode laser and fixed frontal probe. Solid forms of formamide, urea, 3-methylpyridine, aniline, indene, 1-(2-aminoethyl)piperazine, benzofuran and indoline were detected unambiguously under field high-mountain conditions. The main Raman features (strong, medium and partially weak bands) were observed at their correct wavenumber positions (spectral resolution 7-10 cm⁻¹) in the range 200-2000 cm⁻¹. The results obtained demonstrate the possibility of applying a miniaturised Raman spectrometer as key instrument for investigating the presence of nitrogen-containing organic compounds and biomolecules under low temperature field conditions. Within the payload designed by ESA and NASA for future missions focusing not only on Mars, Raman spectroscopy will be an important non-destructive analytical tool for the in-situ identification of both organic and inorganic compounds relevant to life detection on planetary surfaces or near sub-surfaces.     

X-ray Spectromicroscopy of Mineral Intergrowths in the Santa Catharina Meteorite

This work describes the application of microfocus X-ray absorption spectroscopy (XAS) and X-ray photo-emission electron microscopy (XPEEM) to the study of the complex mineralogical intergrowths within the Santa Catharina meteorite. The Santa Catharina meteorite of this study (BM52283 from the meteorite collection of the Natural History Museum, London, UK) primarily comprises a taenite bulk host phase (Fe:Ni ratio = 70.9 ± 0.8%:29.1 ± 0.8%) with a set of oxide-bearing cloudy zone textured regions (Fe:Ni:O ratio = 40.4 ± 0.3%:49.0 ± 0.7%:10.6 ± 0.8% at the core and Fe:Ni:O ratio = 34.4 ± 1.5%:42.7 ± 0.6%:22.9 ± 1.8% towards the rims) and numerous schreibersite (Fe:Ni:P ratio = 38.6 ± 1.6%:38.4 ± 0.9%:23.0 ± 0.5%) inclusions. Between the schreibersite and the taenite are rims up to 50 μm across of Ni-rich kamacite (Fe:Ni ratio = 93.4 ± 0.4%:6.6 ± 0.5%). No chemical zoning or spatial variations in the Fe and Ni speciation was observed within either the schreibersite or the kamacite phases. The oxide-bearing cloudy zone textured regions mostly comprise metallic Fe–Ni alloy, predominantly tetrataenite. Within the oxide phases, the Fe is predominantly, but not entirely, tetrahedrally co-ordinated Fe³⁺ and the Ni is octahedrally co-ordinated Ni²⁺. Structural analysis supports the suggestion that non-stoichiometric Fe₂NiO₄ trevorite is the oxide phase. The trevorite:tetrataenite ratio increases at the edges of the oxide-bearing cloudy zone textured regions indicating increased oxidation at the edges of these zones. The spatial resolution of the XPEEM achieved was between 110 and 150 nm, which precluded the study of either the previously reported ∼ 10 nm precipitates of tetrataenite within the bulk taenite or any antitaenite.     

水体富营养化状态对城市河道底泥吸附/释放P的影响 ——以江苏省苏州市河道试验研究为例

以苏州古城区内的河道为研究对象,采用静态培养的方式,研究了上覆水体不同富营养化程度对底泥中P释放/吸附的影响。研究结果表明：截断外源污染后,苏州河道底泥对水体中营养盐P呈现吸收状态;随着上覆水体磷酸盐浓度的增大,单位面积底泥累积吸收的磷酸盐就越多;上覆水与底泥比值越大,底泥对P的吸附率有减小的趋势。     

On variations in the fine-structure constant and stellar pollution of quasar absorption systems

At redshifts   z _abs≲ 2  , quasar absorption-line constraints on space–time variations in the fine-structure constant, α, rely on the comparison of Mg  ii and Fe  ii transition wavelengths. One potentially important uncertainty is the relative abundance of Mg isotopes in the absorbers, which, if different from solar, can cause spurious shifts in the measured wavelengths and, therefore, α. Here we explore chemical evolution models with enhanced populations of intermediate-mass (IM) stars, which, in their asymptotic giant branch phase, are thought to be the dominant factories for heavy Mg isotopes at the low metallicities typical of quasar absorption systems. By design, these models partially explain recent Keck/HIRES evidence for a smaller α in   z _abs < 2  absorption clouds than on Earth. However, such models also overproduce N, violating observed abundance trends in high- z _abs damped Lyman-α (DLA) systems. Our results do not support the recent claim of Ashenfelter et al. that similar models of IM-enhanced initial mass functions (IMFs) may simultaneously explain the HIRES varying-α data and DLA N abundances. We explore the effect of the IM-enhanced model on Si, Al and P abundances, finding it to be much less pronounced than for N. We also show that the ¹³C/¹²C ratio, as measured in absorption systems, could constitute a future diagnostic of non-standard models of the high-redshift IMF.     

Tracing the warm–hot intergalactic medium in the local Universe

We present a simple method for tracing the spatial distribution and predicting the physical properties of the Warm–Hot Intergalactic Medium (WHIM), from the map of galaxy light in the Local Universe. Under the assumption that biasing is local and monotonic we map the  ∼2 h ⁻¹ Mpc  smoothed density field of galaxy light into the mass-density field, from which we infer the spatial distribution of the WHIM in the Local Supercluster. Taking into account the scatter in the WHIM density–temperature and density–metallicity relation, extracted from the z = 0 outputs of high-resolution and large-box-size hydrodynamical cosmological simulations, we are able to quantify the probability of detecting WHIM signatures in the form of absorption features in the X-ray spectra, along arbitrary directions in the sky. To illustrate the usefulness of this semi-analytical method we focus on the WHIM properties in the Virgo cluster region.